Figures released Friday show infection rates of methicillin-resistant Staphylococcus aureus -- referred to as MRSA -- have more than quadrupled in the Northwest Territories since 2007. And although the bug is still most often spread in hospitals in southern Canada, it is now more common in the N.W.T. among the general population, especially in its smaller communities.

"It's one of our top concerns," said Dr. Kami Kandola, the N.W.T.'s deputy chief public health officer. "It is one our priorities because this particular bug is quite nasty."

There have been 142 cases so far in 2012. The next highest year, 2010, had 138 over the full 12 months.

The territory's latest MRSA figures show an infection rate of 4.3 cases per thousand residents. That's more than four times the 2007 rate of one per thousands residents.

"That's quite high," said Andrew Simor, a doctor at Toronto's Sunnybrook Hospital who has published research on MRSA.

Simor said few other jurisdictions track MRSA infections acquired outside hospitals, but the N.W.T. figures are likely to be tops in the country.

"I suspect that is substantially higher than it would be in most other areas of the country. There's no way to be sure but it would be hard for me to imagine similar rates in Ontario or the Maritimes."

The only province that does track community-acquired MRSA is Alberta, Simor said. There, the infection rate in 2008 was 0.2 per thousand -- less than one-seventh the N.W.T.'s rate that year.

Community-acquired MRSA is becoming more common everywhere in Canada, said Simor. But the N.W.T. is one of the few places where it is now more prevalent than hospital infection.

MRSA normally attacks the skin and soft tissues, leaving them inflamed, painful and sometimes pus-filled. The infection can spread to internal organs and can also lead to more serious conditions, including pneumonia or flesh-eating disease.

Penicillin and similar antibiotics no longer work on MRSA.

"In most situations it's not life threatening, but it can be quite severe," Simor said.

"I have a healthy respect for this organism. There are times when infection can be lethal."

The N.W.T.'s strain of the bug is particularly fierce, said Kandola.

"The one we have, Strain 10, it tends to be a little more virulent," she said.

Since 2008, 55 people have been hospitalized in the N.W.T. with MRSA infections. Five of them had to be flown south for treatment and two died.

Infection rates are highest among infants and in the territory's small, remote communities, where housing tends to be more overcrowded.

Teaching people living in those conditions preventative measures such as regular hand-washing and not sharing towels is a big part of the N.W.T.'s strategy to combat the infection, Kandola said. The territory has only two oral antibiotics that work against MRSA and doctors don't want to over-prescribe them and allow the bacteria to build up resistance.

"The stronger control we have over the transmission, the better it is," Kandola said. "We don't want to flash forward five or 10 years and find out we don't have any more antibiotics left to combat this bacteria."